Safety pilot burner



Feb. 23, 1943.

H. T, SPARROW v SAFETY PILOT BURNER.

Filed June 15; 19 40 Fig.1

IINVENTOR R Huherf T. Sparrow )5 ATTORNEY Patented Feb. 23, 1943 UNITED STATES SAFETY PILOT BURNER.

Hubert T. Sparrow, to Minneapolis- Minnespolis, IMinm, assignor oneywell Regulator Company,

The present invention is concerned with pilot burners and more particularly those of the type which have associated therewith a thermally temperature responsive member adapted to control the operation of a control device.

It is quite conventional in the fuel fluid burning art, particularly where the fuel is gas, to provide a pilot burner construction which incorporates some temperature responsive means for indicating whether the pilot is burning or not.

ment in such an arrangement and due to the many advantages of the thermocouple in this connection, thermocouple safety pilots have been widely used in recent years. It is broadly an obiect of this invention to provide a safety pilot of this type which is extremely compact, in which the burner flame is effectively utilized both as an igniting flame and also to heat the thermocouple or thermocouples,'an d in which the thermocouple is of a type which furnishes a relatively large amount of power.

The object of the invention is accomplished by providing an extremely flat burner and a flat temperature responsive element which is subjected to a relatively long burner flame. The temperature responsive element is in the form of a fiat thermocouple formed of one or more pairs of strips of material of different thermoelectric characteris tics, the lateral edges of which strips are Joined together adjacent their ends. By projecting the flame from an inclined burner face, a single flame is able to serve both as an igniting flame'and also as a means for heating the thermocouple. The burner opening consists of a slit through a removable closure member so that the size of the burner opening can be readily adjusted by the selection of a closure member having a suitable slit. The burner head is provided with slots in its side which serve the dual function of providing mountingjlanges and also of facilitating the introduction of the primary air into the burner. The burner construction further provides an ingenious method of mounting the thermocouples which utilizes a lug over which ,the thermocouple members are placed and which lug also may serve as a means for mounting the burner.

Other features and objects of the invention will be apparent from a description of the accompanying specification, claims and drawing of which Figure Us a perspective view of one form of the improved burner construction.

section having fled form of the burner Figure 2 is a vertical sectional view of the burner construction of Figure 1,

Figure 3 is an end elevational view of a modiconstruction,

Figure 4 is an exploded view of the thermopile utilized in the construction of Figure 3,

Figure 5 is a view of a burner control system employing the improved burner construction as a pilot burner and showing one method of mounting the pilot burner, and

Figure 6 is a view of a main burner and the improved burner mounted in a somewhat diiferent manner than in Figure 5.

Referring to the drawing, the burner head is generally indicated by the reference numeral Ill and the thermocouple member by the reference numeral II. It will be noted that the burner head l0 consists of a block of rectangular cross an inclined forward face I4. At the lower end of burner head I0 is a cylindrical recess I B and communicating with this recess is a passage IS. The passage IB connects with a groove ll extending transversely to the burner, this groove l1 being in the inclined face It. The groove l1 extends over the greater length of the face it terminating just short of the ends thereof. A groove I9 is cut in the right hand face of the block it so as to provide a flange 20. A closure plate 22 which may be formed of sheet metal is secured over the inclined face H by means of curved portions 23 and 24 which extend over the uppermost edge of the burner head I 0 and over the flange 20. The closure plate 22 is provided with a slit 25 therethrough which is of substantially the same length as the groove IT. This slit 2!, as will be apparent from the later description, serves as a burner opening.

The lower end of the recess I5 is threaded so as to facilitate the securing therein of a jet member 21. This Jet member has an intermediate hexagonal portion 28 for the application of a wrench the first place, which serve as head. The flange 36 is provided with an opening 31 to accommodate a bolt, cap screw, or other similar fastening member. The slot is of sufiicient depth so that there is only a thin wall between the bottom of the slot and recess it. An aperture 88 extends through this wall so as to provide a passage for primary air to the interior of the recess i5. By reason of the slot 35, the air needs to pass only through a relatively thin with in going into the recess IS.

The gas in passing through the relatively small final passage of Jet member 21 issues from the jet member with considerable velocity and draws with it air through the openings 38. In passing through passage 18, the air and gas are thoroughly intermixed so as to form the desired combustible mixture. The gas mixture when it reaches the groove I1 is forced to spread out along the groove by reason of the relatively small size of the slit 2!. g The result is that the gas issues along the slit 25 to produce a relatively long burner flame. By reason of the inclination of the wall}! and the corresponding inclination of the closure plate 22, the burner flame is inclined towards the right as indicated in Figure 2.

By providing a separate closure plate H and by making this removable, several advantages are obtained. In the first place, the machining operation is greatly simplified, as will be readily apparent. Furthermore, if the burner becomes clogged at any time due to the accumulation or gummy materials contained in certain types of gas, the closure plate H can be readily removed by sliding the same endwise. This exposes the channel l'! and facilitates the cleaning of the interior burner. Moreover, it is often desirable to have diflerent sized burner openings with different types of fuel. It will be apparent that this (an be readily accomplished with a burner construction of the present invention by providing closure plates having slits of different cross sectional area.

The portion of the device which has been described so far is solely that portion which functions as the burner. The design of the burner, however, is such as to facilitate efllcient operation with a temperature responsive element,

particularly with a thermocouple member. The thermocouple member H which is employed in the construction oi Figures 1 and 2 is substantially of the type disclosed in Patent No. 2,278,744 issued April 7, 1942, to Hubert T. Sparrow and John M. Wilson. This thermopile comprises a plurality of strips 38. 50, M, and 42. Strips 38 and li are of one material and strips M! and 62 of another material having thermoelectric properties which are quite dissimilar than those of strips 39 and ii. Thus strips 39 and M may, for example, be formed of Constantan, an alloy composed of approximately copper and 50% nickel and strips 48 and 42 may be formed of stainless steel. It will be understood that in place of Constantan and stainless steel any two other metals having proper thermoelectric characteristics may be employed. As indicated in the copending Sparrow and Wilson application referred to above, the individual strips may be secured together by rolling whereupon slots ll, 45, and can be out out to cause the elements to be separated except at the opposite ends. The

result is that the elements are secured together so as to form two series connected thermocouples, the hot junctions of which are constituted by the functions at the upper ends between strips 38 and it and between strips ii and 42. The lower ends of strips 39 and 42 are turned outwardly to provide terminal ears 48 and 49. The right hand surface of the burner head is provided with a projecting portion 8|. Extending to the right from this portion is a stud I52 which is of rectangular cross section. The stud is threaded on the upper and lower edges. The thermopile II is disposed over the stud 52 having an aperture therethrough which conforms in configuration to the cross section of the stud 82. This aperture is not shown in connection with the species of Figures 1 and 2 but is shown in Figure 4 in connection with the modifled form. In this flsure the aperture in question is designated by the reference numeral 53 and it is to be understood that an aperture similar to aperture 53 in size and location is provided in the thermopile unit ll. Strips 55 and 58 of heat resistance insulating material such as mica or asbestos are interposed on each side of the thermopile II to prevent short circuiting of the various component strips. The rigid sheet metal plate I is placed over the strips 58. This plate 58 as indicated in Figure 1 is grooved at 59 and III to provide ribs on its inner surface. -'These ribs are so located as to force the insulating sheet ii in between the component strips of the thermopile. This serves not only to more effectively insulate these strips from each other but also to more securely position the thermopile. A nut 62 is threaded onto the stud 52 and serves to clamp the entire assembly including insulating strips 55 and 58, thermocouple unit H and plate 58 together against the burner head ill. By reason of the ribs provided by grooves 59 and i0 and by reason of the non-circular aperture]! which closely conforms with the non-circular cross section of stud 52, the thermopile II is free from any tendency to turn about the stud B2. In this manner the single nut 62 is eflective to hold the thermopile ll rigidly in position. The hot Junctions of the thermopile, it will be noted, are in the path of the flame issuing from the slit 2!. The flame issuing from slit 25 is thus able to thoroughly heat the hot junctions and at the same time be available for its normal igniting function. As will be more clearly brought out later the diagonal path followed by the flame enables the burner .to be mounted in either horizontal or vertical position with the assurance that in either case, the -hot junctions of the thermocouple will be adequately heated by the burner flame.

The right hand end of the stud 52 is provided with an aperture 63 which is designed to receive a fastening member such as a bolt or screw. The stud 52 thus not only serves as a means for securing the thermopile in, position but also may serve as a mounting means for the burner unit.

Species of Figures 3 and 4 The species of Figures 3 andi is identical to that of Figures 1 and 2 as far as the burner construction is concerned. For this reason, the burner construction will not again be described in detail and the reference numerals applied thereto are the same as used in connection with each thermopile comprises two pairs strips of dissimilar metals, these strips being connected together in series. The only difference between the units I2, I3, and I4 and the unit II is that the terminal lugs I8 and I9 corresponding to terminal lugs 48 and 49 are from necessity on diflerent units. Thus terminal lug I8 is on unit I2 and terminal lug I! on the unit 16. Each of the units is provided with an aperture 83 which corresponds in configuration to the cross section of the lug 52. The units I2, I3, and I4 are assembled together on the lug 82 with insulating strips-89, 8| l2, and 83 to separate them from the burner head and from each other at desired points. The insulating strips 80 and B8 are of the same area as the clamping plate 85 corresponding to clamping plate 58. vIn other words, these two insulating strips cover the entire possible area of contact between units 12 and burner head I6. and between units 14 and clamping plate 84. The insulating strips 8| and 82 are however provided with cut away portions to permit connection of the various units together. Thus referring to Figure 4, the insulating strip Si is provided with a rectangular cut away portion 8-3 while the insulating strip 82 is provided with a cut away portion 81. The member 88 of conducting material and of the same area as the cut away portion 86 is designed to fit into the cut away portion and electrically connect the extreme right hand strips of units I2 and 78. It is to be understood that the conducting member 88 may be secured to these strips by brazing or some other suitable manner to provide a joint of low resistivity. Similarly the member 89 of conducting material is provided to lit into the cut away portion 81 and to electrically connect the left hand portions of units I3 and I8. This conductor member 89 is shown in position in Figure 3. By the use of the conductor members 88 and 89, the three units I2, 18, and is are connected in series so as to collectively provide six series connected thermocouples.

Referring to Figure 3, it will be noted that the thermopile unit 13 is somewhat longer than the unit 12 and that the unit 16 is in turn somewhat longer than the unit I8. The result is that the flame is able to contact a substantial portion of the hot junction of each of these units.

Application 0] burner structures In Figure 5, as shown in schematic form, a burner control system utilizing the improved pilot burner of the present invention. A main gas burner is indicated by the reference numeral 82, this gas burner being supplied with gas by the electromagnet. On the other hand. the switch may be one which-requires manually re-. setting of the switch. Such a switch is shown in the patent to Kronmiller No. 2,165,801 for 1 Switch" issued July 11, 1939.

The current for operation of valve $6 is supplied by a step down transformer I62 which has its. primary side connected to line wires I93 and IN.

The energization of the valve 96 is controlled by a thermostat I05, this thermostat comprises a bimetallic element I08 to which is secured a contact arm IBI. This contact arm is designed to engage with a fixed contact I08. A magnet its is positioned adjacent the contact arm I91 and is designed to cause the contact blade I01 to engage with and separate from contact I08 with a snap action. The bimetallic element I06 is so disposed that upon a temperature fall, the contact arm I01 is moved into engagement with com tact I68. I Upon the temperature to which bimetallic element I88 is subjected falling to a predetermined value, the contact arm IE1 is moved into engagement with contact I 08. This results in the establishment of an energizing circuit to valve 96 as follows: from transformer I62 through conductor IIB, contact I08, contact arm I91, bimetallic element I68, conductor Iii, switch Iii, conductor H8, valve 98 and conductor 6 back to the transformer I02. This circuit is established only if switch ISI is closed and switch Ifil is closed only when current is suppliedto the elec-- tromagnet thereof by the thermopile II. Thus it is assured that the valve can never be enersized and hence opened unless the thermopile II a pipe 83 from a mixing chamber 94. The mixing chamber is in turn connected through a pipe 95 with a motorized gas valve 98 which has a gas supply pipe 81 connected to the inlet side thereof. Themotorized gas valve 98 is of any suitable type which remains open as long as it is energized and is closed by gravity or other suitable biasing means upon deenergization. The pilot burner I0 is securedto the main burner 92 by means of the stud 52. The burner head is connected to a gas supply pipe 98 which in turn is connected to the gas supply pipe 91 on the inlet side of valve 88. The thermopile II is connected by means of conductors I00 to an electromagnetlcally operated switch "II of any suitable type designed to be operated by the current from a :hermcpile. For example, the switch may be of :he type which is moved to closed position against a .biasing means upon energization of is heated by the pilot burner flame. If at any time the pilot burner flame is extin uished, the temperature of the hot and cold junctions of the thermopile will rapidly equalize to cause the thermopile to cease to generate current. The switch I 9! will then move to open position and cause deenergization of the valve 96.

In the arrangement of Figure 5, the pilot burner was mounted vertically by means of the stud 52. In Figure 6, the pilot burner is shown as mounted horizontally through the flanges 86.

It will be noted that the burner head I0 is iastened to a bracket H5 which in turn is secured to a burner IIB. It will be noted that even though the burner is mounted horizontally the flame is still effective to both heat the hot Junotion of the thermopile II and also extend over the main burner so as to be capable of Igniting the gas issuing from the same.

It will be seen that I have provided an extremely compact and highly effective assembly of a pilot burner and temperature responsive element. With this arrangement it is possible by the use of the relatively compact arrangement shown to generate a relatively large amount of power.

While I have shown a specific embodiment of the invention for purposes of illustration, it is to be understood that the invention Is to be limited only by the scope of the appended claims.

I claim as my invention:

1. The combination comprising, a burner body having a relatively flat base portion, a burner head for said burner body encasing an elongated ing a plurality of cold junctions secured to the relatively flat base portion of said burner body and the hot junctions thereof extending along and adjacent to the said elongated burner orifice.

2. In combination, a relatively flat burner head having a portion formed for connection with a fuel supply conduit and a passage extending from said portion through said burner head, said burner head being provided with an elongated slit communicating with said passage at the opposite end thereof from said connecting portion, and a flat thermocouple member secured to said burner head with its hot junction adjacent said slit, said thermocouple member comprising two flat relatively thin strips of materials of dissimilar thermoelectric characteristics. the lateral edges of which are joined at one end to provide the hot junction of the thermocouple, the width of said thermocouple adjacent said hot junction being substantially equal to the length of said slit.

3. In combination, a relatively flat burner head having a portion formed for connection with a fuel supply conduit and a passage extending from said portion through said burner head, said burner head being provided with an elongated slit communicating with said passage, and a plurality of flat thermoelectric current generating members secured to said burner head in spaced, superposed relation so that one end of each of said members is adjacent said slit and extends the full length thereof and so that the flame issuing from said slit successively contacts said ends.

4. In combination, a relatively flat burner head having a portion formed for connection with a fuel supply conduit and a passage extending from said portion longitudinally through said burner head, said head being provided with a groove extending perpendicularly to said longitudinal passage at the opposite end of said head from said connecting portion and forming with said longitudinal passage a T-shaped passage for the fuel, a closure member secured to said burner head over said groove, said closurev having a slit therethrough substantially coextensive with said groove, and a flat temperature responsive element secured to said burner head with a portion thereof adjacent said slit and extending the full length of the slit.

5. In combination, a burner head of substantially rectangular cross section having a passage extending longitudinally therethrough and a flame opening communicating with said passage, a temperature responsive element secured to said burner head with a portion adjacent said opening, a slot formed in a side wall and forming two side flanges, one of said flanges having an opening therethrough to accommodate fastening means for securing said burner head and temperature responsive element to a support, said slot being of a depth such as to provide only a relatively narrow separating wall between said slot and said passage, and said separating wall having an aperture therethrough to said passage to provide an air inlet for the burner.

6. In combination, a burner head, a burner jet extending into a recess in said head, said head having a passage extending from said recess longitudinally therethrough and a flame opening communicating with said passage, a temperature responsive element secured to said burner head with a portion adjacent said opening, a slot formed in a side wall and forming two side flanges, one of said flanges having an opening therethrough to accommodate fastening means for securing said burner head and temperature responsive element to a support, said slot being of a depth such as to provide only a relatively narrow separating wall between said slot and said recess, and said separating wall having an aperture therethrough to said recess at a point adjacentsaid jet to provide an air inlet for the burner.

'7. In combination, a relatively flat burner head having a portion formed for connection with a fuel supply conduit and a passageextending from said portion through said burner head to a relatively long and narrow burner opening extending transversely of said burner head, a plurality of flat thermoelectric current generating members secured to said burner head in spaced superposed relation so that one end of each of said members is adjacent said burner opening, said ends being disposed in stepped relation with the end most remote from the opening projecting furtherest upward so that the flame issuing from said opening successively contacts said ends, and means for electrically connecting said members in series.

8. Incombination, a burner head having a portion formed for connection with a fuel supply conduit and a passage extending from said portion through said burner head to a burner opening, a plurality of flat thermoelectric current generating members secured to said burner head in spaced superposed relation so that one end of each of said members is adjacent said burner opening and so that the flame issuing from said opening successively contacts said ends, and means for electrically connecting said members in series, each of said members comprising at least one pair of flat strips of materials of dissimilar thermoelectric characteristics, the lateral edges of which are joined at one end.

. HUBERT T. SPARROW. 

